British Jet for BOB?

[Soren]

AL,

Those are the official performance figures for the Me-262.

Eric Brown tested the Me-262 for the RAE and during the speed trials the top speed was established as 900 km/h in level flight. There's a video on Youtube where Eric Brown comments this qouting the top speed as 568 mph:
View: https://www.youtube.com/watch?v=RACSnJDrfgA

The reason for the extremely conservative official figures from Messerschmidt was the full awareness of how much performance varied from batch to batch of Jumo 004 engines. The one Brown tested apparantly had a very good surface finish and good engines.

And about the P-80A, IIRC it wasn't up until late 1945 that a top speed of 556 mph was reached, the P-80's in Europe are said to hve had a top speed around 770 km/h, not much.

 

[AL Schlageter]

Cherry picking results? Look at the graph and the Me262's mean speed was 800-840kph (500-520mph) with only a very few doing better.

The Jumo 004B had an output of 8.8kN

That must have been one of the exceptionally good engines produced.

With the right metals the 004B could maintain 9.8kN for 10 hours

That must have been one of the truly exceptional good engine produced.

 

[Soren]

Cherry picking results? Look at the graph and the Me262's mean speed was 800-840kph (500-520mph) with only a very few doing better.

Here's the official top speed figure gathered from multiple test flights as the average [Notice the results are listed as Erflogene Werte!= test flown]:

840 km/h at SL, 870 km/h at 6km.

That must have been one of the exceptionally good engines produced.

Why ? 8.8 kN is the official output of the production series 004.

That must have been one of the truly exceptional good engine produced.

No, it just consisted of the right heat resistant metals.

 

[davparlr]

AL,

And about the P-80A, IIRC it wasn't up until late 1945 that a top speed of 556 mph was reached, the P-80's in Europe are said to hve had a top speed around 770 km/h, not much.

The P-80s sent to Europe were YP-80As, preproduction versions of the P-80 and, of course, some could have performed below par. However, the earlier XP-80A was capable of 553 mph (857 km/hr) and the production P-80A (production P-80As were starting delivery in February 1945) was capable of the 558 mph number. So if the first P-80s reaching Europe did not reach this range, there were problems with those particular aircraft.

 

[davparlr]

AL,

Those are the official performance figures for the Me-262.

Eric Brown tested the Me-262 for the RAE and during the speed trials the top speed was established as 900 km/h in level flight. There's a video on Youtube where Eric Brown comments this qouting the top speed as 568 mph:
View: https://www.youtube.com/watch?v=RACSnJDrfgA

As we have discussed many times before, pilots without proper instrumentation, TAS indicator or as a minimum, outside air temperature, are not a reliable source of true airspeed information. Now, maybe this was a test aircraft and was properly instrumented and therefore is a valid data point. If not, I would doubt it.

 

[kool kitty89]

The only disadvantage speed-wise with the YP-80 was that the air-intakes had not yet been fitted with boundary-layer bleeds (iirc) so there would be buffeting at high-speed (~550 mph iirc) which could lead to flame-outs. Otherwise, with the exception of the fuel-pump auxiliary pump and the lack of tip-tanks, the YP-80s were identical to early production P-80As (using 3850 lbf J33s, later P-80A's used 4,000 lbf engines).

In fact, this would have made the YP-80 higher performing at it's max take-off since it couldn't hold external stores and thus the weight would be 12,000 lbs with max 485 US gallons internal fuel. Note that this is considerably less than the Me 262 (which was only 400 lbs heavier empty) but thanks to the low SFC of the J33 engine, it still had more range than the 262 at ~780 miles combat for the 262's ~650 miles.(using the 004B)

One other advantage centrifugal designs have over axial designs is survivability. Unless the turbine is hit, little damage will result (from bullets, not cannon shells), probably why the Mig 15 could take so many .50 cal hits. While the compressor of an axial design is very sensitive to damage.

Also, several millitary trainers (new designs in the '60-'70s) still use centrifugal designs. As did early models of the T/A-37 Tweet/Dragonfly (Turbomecca I believe) at least in foreign service. And the Aero L-29 Delfín - Wikipedia, the free encyclopedia certainly did.

 

[AL Schlageter]

Here's the official top speed figure gathered from multiple test flights as the average [Notice the results are listed as Erflogene Werte!= test flown]:

840 km/h at SL, 870 km/h at 6km.

Why ? 8.8 kN is the official output of the production series 004.

No, it just consisted of the right heat resistant metals.

The comment on the engines was in reply to your statement:
The one Brown tested apparantly had a very good surface finish and good engines.

So multiple tests were flown with a 'Brown' type plane. Notice in the graph I posted there is well over 50 speeds plotted.

 

[davparlr]

Also, several millitary trainers (new designs in the '60-'70s) still use centrifugal designs. As did early models of the T/A-37 Tweet/Dragonfly (Turbomecca I believe) at least in foreign service. And the Aero L-29 DelfÃ*n - Wikipedia, the free encyclopedia certainly did.

I had the pleasure of flying both types, the centrifugal (T-37), and axial (T-38/C-141) and can make some comment. First, you are right about the durability of the centrifugal compressor. The T-37 engine was practically indestructable. There was no rainfall limit on the T-37 engine and we felt we could probably fly through a waterfall with no problem. There was also a story going around about a T-37 that, after pilot bailout, slid to a stop on the desert floor. When the AF got to the plane, the engines were still running and sucking in bushes and other desert things. An issue with the T-37 was spool up time, or rather, lack of it. I remember that after stall practice, running the throttles full up. All I got was a gradually increase volume of whine. After several seconds of increasing pitch, the RPM finally got above 90% and a welcoming push in the back was felt. To make go-arounds safe, final was flown with speed brake out and thrust attenuaters out (panels that extended into the jet exhaust) so RPM had to remain high. On go-around, both were retracted and instant acceleration was available. Now possibly more advanced centrifugal compressor engines may have elimiated some of this. May be someone who flew an F9F or T-33 could comment.

Now the T-38 was quite different. It was not particularly rugged, unable to penetrate heavy rainfall and only slight icing (the compressor blades were like razor blades). Response time was amazing. Almost instant power. It was no problem getting power for go-arounds (especially with ABs), which, was nice since it was a hot plane on final. The C-141 engines were as rugged as the T-37, but the engines were big with large fan blades that were slow turning (for a jet). Spool up time was quite reasonable.

 

[kool kitty89]

Ok, I've checked a few things. It was only the T-37 that used the centrifugal J69 (lisenced Turbomeca Marboré - Wikipedia, the free encyclopedia) while the A-37 used J85s. (far more powerful than even the uprated ~1,900+ J69s at 2,855 lbf, and the T-33's engines were only ~1,000-1,100 lbf) Incedentally the J85 is what the T-38 uses too, albeit with an afterburner allowing another 1000 lbf, at 3,850 lbf total.

About the spool-up, I wouldn't expect the T-33 or F-9 Panther's engines to be much better as they are older designs and larger, though spool-up is far better than that of the 004 engine. I'm not sure about the 003, but the HeS-30's spool-up was probably better than the centrifugal designs as were J30 and J34 axial engines used in the McDonnell FH Phantom and F2H Banshee were probably better too.

One thing you have to realize between the J69 (Marboré
) and the J85, is the J85 is extremly advanced and was developed about 10 years later. Turbomeca developed the Marboré in the late 1940s as a light-weight low-cost design iirc.
While the J85 was developed as a small Millitary class engine. The J85 is capable of 5,000 lbf in its most powerful forms and is (still) the most powerful engine for weight in the world (highest thrust/weight) at over 7.7:1.
It is also extremely compact with a diameter of only 17-18 in wide (22-26 in with afterburner) and only around 400lbs. (~600 lbs with afterburner)

Though the J69 isn't too shabby either at nearly 5.5:1 at it's highest. With the 1920 lbf 350 lb J69-T-41A. And at 22 in diameter. But this is with an added axial stage, some experimental versions made over 2,500+ lbf with 2 axial stages added. But the single-stage centrifugal ones of the T-37 only produced 1025 lbf for around the same size and weight.

 

[FLYBOYJ]

And the Aero L-29 DelfÃ*n - Wikipedia, the free encyclopedia certainly did.

As Dave mentioned with the T-37, the L-29's M701 engine is almost indestructible. I've work on and flown these aircraft form almost 10 years now and seen some of them in US owner's hands take some terrible abuse and keep running like clockwork. The M701's lineage comes from the VK-1, derated. You could really see the similarities when you put one of these engines side by side with a J-33.

 

[davparlr]

One thing you have to realize between the J69 (Marboré
) and the J85, is the J85 is extremly advanced and was developed about 10 years later. Turbomeca developed the Marboré in the late 1940s as a light-weight low-cost design iirc.
While the J85 was developed as a small Millitary class engine. The J85 is capable of 5,000 lbf in its most powerful forms and is (still) the most powerful engine for weight in the world (highest thrust/weight) at over 7.7:1.
It is also extremely compact with a diameter of only 17-18 in wide (22-26 in with afterburner) and only around 400lbs. (~600 lbs with afterburner)

I was always amazed at the small size of the J85. It looked like a toy, but boy could it run. It was developed to be the engine of the quail decoy, a one time usage.

 

[kool kitty89]

I read about that too, but it's sure found alot of other uses, particularly civilian. It's also the engine used in the Me-262 Project's reproductions.

They actually had to limit thrust so as to not vverstress the aircraft iirc, or at least limit the high thrust range to take-off and climb so the safe speed isn't exceeded. (though to be honest the plane could probable do 600-620 mph at sl w/out problems, though the original limitations of 950 km/h (589 mph) were placed durring the war, altitude wasn't specified, and indded, the safe mach limit of ~.84 wouldn't be excceded at this speed below ~25,000 ft, and the crit-mach of .86 not below ~30,000 ft)


And the T-37's J69 engine is almost as small overall than non-afterburning J85s, at ~350 lbs and less than 2ft wide and about 4ft long!

And doesent the BAC Jet Provost - Wikipedia, the free encyclopedia look like the T/A-37? And both a/c are trainers/attack aircraft.(ie strikemaster)

 

[davparlr]

And the T-37's J69 engine is almost as small overall than non-afterburning J85s, at ~350 lbs and less than 2ft wide and about 4ft long!

And doesent the BAC Jet Provost - Wikipedia, the free encyclopedia look like the T/A-37? And both a/c are trainers/attack aircraft.(ie strikemaster)

Solid, reliable engine, but, boy what a noise maker. We had to wear ear plugs AND ear muffs when around them. My ears still ring.

 

[red admiral]

If we are to look at designs which only just made it to be finished during the war then the HeS-011 is superior to all of them, with a output of 15.6kN while being very narrow and light it easily beats the heavier RR Nene engine which by then had a max output of 18.8kN.

Eh? The Nene was running at 5000lbf and reliabily instead of intermittant bursts of 2500lbf for the HeS 011.

Of course the Metrovick F.3 blows just about everything out of the water with 4600lbf, weight around 1100-1200lbs and sfc of around 0.60lb/lb-hr

 

[Soren]

The HeS-011 could keep running at 15.6 kN, not just at short bursts.

The Nene had a max output of 18.8 kN in late 1945. The Metrovick F.3 wasn't developed before the late 50's so why would you ever mention this ??

The F.2/4 had a max output of 15.6 kN (same as HeS-011), but weighed more than the Jumo 004B.

 

[AL Schlageter]

The Metrovick F.3 wasn't developed before the late 50's so why would you ever mention this ??

The F.3 was running in Aug 1943.

 

[Soren]

Whats your source on that AL ?

Also wouldn't it be a little strange not to use the F.3 earlier for the Meteor instead of the 15.6 kN RR Derwent in 1954 if it was so good ??

 

[Soren]

Just to rule out any doubt about the official top speed of the Me-262A-1a, notice the written text:

 

[kool kitty89]

You guys, the F.3 is a (rear-fan) turbofan...

And the F.2/4 was probably not used on the Meteor (over the Derwent V and later) for the same reason the F.2/1 lost out to the less-powerful Welland (and later, Derwent I), because of complexity, reliabillity, and ease of maintanence issues. Besides, the Derwent was able to push the Meteor IV to its mach limit in level flight. (though not crit mach, just the safety limit) And gave it a climb of 7000 ft/min, though it couldn't push the F.8, with new (thin, low compressibility) tail, to the increased Mach .82 limit.

And FYI, the F.2/4 made up to 4,000 lbf (17.8 kp) by the late 1940s. And from what Red-Admeral said, the HeS-011 never made the designed expansion to 3,000+ lbf, though it did produce the originaly specified 2860 lbf (1300 kp) iirc.

But in terms of fuel efficiency, thrust/weight, low frontal diameter, and reasonable complexity and practical time-frame, it has to go to the HeS-30 (109-006). It was the best class I engine the germans had, and should have been ready for production around the same time as the 004B, if not earlier. It was not beaten in overall characteristics untill the extremely compact (19 in) 1600-1700 lbf Westinghouse J30 at just ~660 lbs was running just prior to the end of the war. Though thrust output was somewhat less, it was developed into the excelent (25 in) J34 which produced over 3000 lbf and weighed ~1,100 lbs.

Both the J30 and the HeS-30 were better overall designs than the HeS-011, in terms of thrust/weight, fuel efficiency (particularly in the J30), thrust realitive to frontal area, and probably spool-up time too. The J30 was around the same stages of development as the 011 at the same time. The HeS-30 beats both of them at running at 900+ kp in early 1942!

The HeS-8 could have been a good practical engine had it made its designed thrust. (700 kp planned, 550 produced, 600 with added axial stage and air-flow improvements) This fact in mind, it may have been better to work on improving the HeS-6 as an intrim/backup for the axial designs, though most a/c would have to alter the wings for mid-mounting (like the meteor) to allow adequate clearance with normal sized landing gear. Clearly though, the axial designs should be replacing them (particularly the HeS-30; 006) by Mid 1943.(should be in production by early '43) It was actually still quite smaller than Whittle's W.2 at ~39 in (1.0 m) in in diameter (compared to the Welland's ~44 in diameter) and only slightly wider than the HeS 3's ~36 in (.93 m) (despite being ~17% heavier than the HeS 3) due to more compact folding and stretching of the combustor than in the HeS 3.
And the HeS 6 was producing 1300 lbf at decent SFC (<1.6 lb/lbf/hr) in late 1939! Thrust that the the HeS 8 wasn't making untill 1942 (with the addition of the axial compressor stage and improved diffuser). Though the 004A was beating this by far by late 1941 (albeit at much higher SFC and weight), as was the prototype HeS-30 (at lower SFC and weight than the HeS 6), the 003 was still struggling to top 1100 lbf when the Me 262 V1 used them (before they quickly failed) in 1942.

 

[renegate326]

I'm not quite sure why Von Ohain is credited with being the co-inventor of the jet engine when he received the full plans of Whittle's engine of 1930 from the German embassy in London. Von Ohain's engine is basically identical to Whittle's patent apart from the radial outflow turbine, adopted for heat considerations.

Considering that Whittle also invented a number of turbofans, reheat and the turbodrill he is far too much overlooked. The Whittle design turbojet went from 850lbf to 2500lbf in the W.2/700 with very little change in size and weight. For the M.52, the W.2/700 was to be developed into a duct-burning turbofan producing over 5000lbf. Not bad for something built in an outhouse on a shoestring.

Revelling in fantasy mate..Whittle and Von Ohain met in the US in 1978 and compared their respective designs and Whittle acknowledged that German concept was different than his...You should informed yourself a little better before posting nonsense..Yes co- inventors totally independent from each other. But germans were ahead in overall technology as in addition to von Ohain they also had brilliant engineers like Dr ANSELM FRANZ and Dr HERBERT WAGNER to whom we owe our high -bypass turbofan engines of today like RR Trent series , ring a bell?